1. Field of the Invention
This present invention relates to a transformer, and more particularly, to an integrated stacked transformer.
2. Description of the Prior Art
Transformer and BALUN are the important components in radio frequency integrated circuit to implement single-ended to differential conversion, signal coupling, and impedance matching, etc. With integrated circuit developing toward system on chip (SOC), integrated transformer/BALUN replaces traditional discrete component gradually, and is applied in radio frequency integrated circuit widely. However, the passive components in integrated circuit such like inductor and transformer consume a lot of chip area in general cases. Therefore how to reduce the amount of passive component/components in integrated circuit and minimize the area of passive component/components and maximize the specification of component/components like quality factor Q and coupling coefficient K in the same time is an important issue.